Turning on a gene found in wheat could boost levels of protein, iron and zinc, scientists have discovered.

The gene occurs naturally in wheat, but has largely been silenced during the evolution of domestic varieties.

Researchers found evidence that turning it back on could raise levels of the nutrients in wheat grains.

Writing in the journal Science, they suggest that new varieties with a fully functioning gene can be created through cross-breeding with wild wheat.

"Wheat is one of the world's major crops, providing approximately one-fifth of all calories consumed by humans," said project leader Professor Jorge Dubcovsky from the University of California at Davis.

"Therefore, even small increases in wheat's nutritional value may help decrease deficiencies in protein and key micronutrients."

'Spectacular' results

The researchers identified a gene called GPC-B1, GPC standing for Grain Protein Content.

It is found in both wild and domesticated varieties of wheat, but in subtly different forms, indicating that it has been changed by the long history of domestication.

The results were spectacular, confirming that this single gene was responsible for all these changes

Jorge Dubcovsky

Working with a variety of wheat called Bobwhite, a staple crop whose grains are commonly used in bread, scientists "turned down" GPC-B1 activity even further using RNA interference.

RNA interference is a recently-discovered technique which blocks the expression of genes.

"The results were spectacular," said Professor Dubcovsky.

"The grains from the genetically modified plants matured several weeks later than the control plants and showed 30% less grain protein, zinc and iron, without differences in grain size.

"This experiment confirmed that this single gene was responsible for all these changes."

The researchers deduced that the reverse process - enhancing GPC-B1 activity - ought to produce plants which have higher levels of these nutrients in their grains and mature faster.

The UC Davis team is already making such varieties, not by genetic engineering but through crossing domesticated wheat plants with wild relatives.

The key is a technology called Marker Assisted Selection (MAS). This allows scientists to select which plants to cross using genetic information, rather than simply choosing them by their attributes, as farmers have done throughout the history of agriculture.